The invention relates to an annular valve for a piston compressor, having a valve seat attached in the housing of the compressor, an absorber attached thereto at a distance and at least one annular sealing component, which can move between the valve seat and the absorber, and at least three helical springs, which move the sealing component in the shutting direction towards the valve seal, being disposed between the absorber and the sealing component, distributed over its periphery. By an annular sealing component is to be understood both an annular member, which cooperates only with one opening or annular duct mounted in the valve seat, and also an annular plate, which cooperates with several openings or annular ducts mounted concentrically in the valve seat.
With known valves of this type having annular plates as the sealing component, the helical springs are only used to bring the sealing component into the closing position and to keep it there. To guide the sealing component during the opening and closing movement, the sealing component was guided either on a spacer ring disposed between the valve seat and the absorber, or so-called control arms, which are manufactured in one piece with the sealing component and the attachment ring, were provided between the sealing component and its attachment ring. Whereas the first-mentioned embodiment does not operate without friction because of the guidance of the sealing component at the spacer ring and therefore has to be lubricated with oil, the second embodiment does operate without friction and is therefore used in oil-free compressors; however it has the disadvantage that it requires more space because of the control arms. Furthermore breakdown may result if the control arms break.